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Thread: R12 to 134A
10-13-2004, 01:14 PM #1Regular Guest
- Join Date
- Apr 2004
- Napoleon, Ohio
I am learning on a small "College Dorm" refridgerator. It is a montgomery ward model B059C-C-WARD. It is an R-12 unit and appears to have had a leak and needs recharged. I would like to put 134A in it. I think I need to evacuate it and replace the oil with a 134A compatable. Is this all correct? What is a good oil and how do I go about filling it with oil. Thank you
10-13-2004, 01:35 PM #2Professional Member
- Join Date
- Aug 2002
Unsweat the compressor. Apply a small amount of nitrogen pressure to the suction process tube, which is not the suction line which you just unsweated.
Holding the compressor at such an angle that all of the oil inside is pressured out.
You are catching this oil in a container to be measured.
The oil should be replaced with POE, which is compatible with 134a.
With the corerrect amount of POE oil inside a clean container, you will hook up a vacuum pump to the process tube and on the other end you attach a short vinyl hose and hold the end down under the oil in the container.
Turn on the vacuum pump and begin sucking the POE oil into the compressor. Once the oil is gone from the container, it is inside the compressor.
Now you can temporarily seal off the ports on the compressor and begin working at flushing out the old oil which is left inside the tubing, evaporator, condensor.
In the old days, we just used liquid R12 and flushed until we saw liquid coming back at us.
Gotta use some expensive flushing solvent!
Choose the non pressurized gallon jug of solvent. Johnstone sells it.
Run that thru your system, component by component.
Honestly, the best method for doing this is simply to "Divide and Conquer".
Seperate the condensor, evaporator and flush them individually.
That leak needs to be fixed.
Aluminum evaporators can be sucessfuly fixed. But you need to know what to do.
An aluminum tubing leak can be soldered with an aluminum flux/ solder combination. But it is tricky.
You will want to pressure test this system once it is back together. Once you believe it is leak free, then install your compressor and replace the old drier in the liquid line.
I like the all Sporlan cap tube drier. Expensive but worth it.
If this is for a class progect, just use whatever they provide you with.
Always, always, always make positively sure the very end of your filter drier is pointing DOWNWARD as it goes to the capilary tube.
That assures a liquid seal at the entrance to the cap tube.
I dont care how they do it in class or what you saw in a text book ... this is the only way to install that drier. Period!
This rule only aplies to small cap tube systems.
When everything is said and done, you evacuate the system down to five hundred microns. Fresh oil in vacuum pump.
Weight in the adjusted amount of 134a. Say good bye to the uniit. It's done.
I left out a few details. I didnt know how much you know. They should go over that simple stuff in class though.